From that looks like line load calibration of sorts. The board seems to overcompensate on voltage when under higher loads.
New to the game but I know typically what I saw in the past was the voltage you set it at, would actually dip when under high loads. Thankfully tech has come a ways where it stays very close to what you set it at if not a minor increase. I'm seeing on my board a .01V increase (Level1) not a full .06V increase line you are.
Though Earthdog is right. Not to much to it these days unless you get into real fine tuning. Though dropping your voltage to give off less heat is the name of the game if you can. Every chips different but mine seems to settle in nicely at 1.35V @ 4.7Ghz.
Now as stability.. yes ideally you'll want to do testing. I don't run Prime95 much anymore due to the amount of time it takes, I typically use IntelBurnTest. Though its not as forgiving as Prime95 typically. If it doesn't work it typically locks up the PC. But you want at least a decent amount of stability, otherwise you could lock up in games.